Charged particle beam apparatuses have many functions in a plurality of industrial fields, including, but not limited to, inspection of electronic circuits during manufacturing, exposure systems for lithography, detecting devices, defect inspection tools, and testing systems for integrated circuits. There is a need for inspection devices operating at a spatial resolution in the micrometer and nanometer range.
Micrometer and nanometer scale process control, inspection or structuring, is often done with charged particle beams, e.g. electron beams, which are generated and focused in charged particle beam devices, such as electron microscopes or electron beam pattern generators. Charged particle beams offer superior spatial resolution compared to, e.g. photon beams because their wavelengths are shorter than the wavelengths of light beams.
High resolution imaging devices based on electron optics systems require low electron-electron interaction for providing a small width of the energy spectrum. In electron microscopes, e.g. the higher an electron current of the electron beam, the higher the electron-electron interaction is. Thus, providing electron beams for inspection purposes having low energy spread and low blur is an issue.